The present invention relates to a coating apparatus for coating a resist solution, for example, on an object to be coated such as a semiconductor wafer, an LCD substrate, etc.
In the fabrication of the semiconductor device, circuit patterns are formed by a so-called photolithography technique in which photoresist is coated on the semiconductor wafer as an object to be processed, then exposed to correspond to the circuit patterns, and then developed.
During the photoresist coating step of these steps, while rotating the semiconductor wafer held on a spin chuck, a resist solution is supplied to a center surface portion of the semiconductor wafer from a nozzle provided over the semiconductor wafer such that the resist solution can be spread over the semiconductor wafer by a centrifugal force. Accordingly, a resist film can be coated uniformly on an overall surface of the semiconductor wafer. In this case, in order to prevent scattering of the resist and a solvent, a cup is provided to surround the semiconductor wafer and then an air whose temperature and humidity are controlled is supplied to an inside of the cup from opening portions of the cup to enable a stable coating.
However, for convenience of loading/unloading of the semiconductor wafer, an inner diameter of the cup is not set smaller than an inner diameter of the semiconductor wafer. Therefore, a sufficient wind speed cannot be obtained around the periphery of the wafer, and also a whistling phenomenon which may be due to a turbulent flow occurs on the outer peripheral portion of the wafer. As a result, the coating film having uniform film quality cannot be formed.
In addition, because of the rebound of resist mist, the peripheral portions of the wafer are contaminated to thus cause particles. Hence, the mist on the peripheral portion of the wafer has been removed by the solvent such as thinner, nevertheless its effect can be not sufficiently achieved because of the rebound of peripheral thinner. In addition, the resist mist has scattered around the cup to thus contaminate the outside of the cup.